A variety of medical devices are known to facilitate the physical destruction and removal of obstructive tissue (e.g., vascular plaque and thrombotic occlusions) or living tissue (e.g., the lining of a Fallopian tube for purposes of sterilization). A class of these devices include a motor, for providing a rotary drive, a cutting tip, and a drive shaft spanning therebetween.
The cutting tip of known devices commonly features a rigid or semi-rigid cutting portion. The cutting portion is used to destroy tissue positioned distal to the device. In addition to, or as an alternative, known devices may also incorporate whips or fibers positioned about a longitudinal, outer periphery of the device. The whips and fibers are intended to engage tissue which surrounds the longitudinal outer periphery of the device. Commonly, the cutting portions, whips, and fibers are constructed of a material sufficient to destroy friable and coagulated tissue as well as surrounding living tissue.
With regard to those devices having rotating or moving whips/fibers, the whips/fibers are commonly predisposed in a substantially normal orientation relative to the device, or they are caused to assume such orientation through the rotation of the device. Known devices of this nature include stiff bristles rotated at slow speeds to gather cell samples or to permanently entangle a thrombus. These devices have particular application in removing deposits or tissue surrounding the diametrical periphery of the bristles but have little use in engaging material or tissue positioned distal to the device.
Rigid or semi-rigid cutting portions which are intended to engage material or tissue positioned distal to the cutting portion traditionally include aggressive rotating prongs, drill tips, or blade-like elements. For these devices, a user must precisely control the longitudinal movement of the device to achieve a desired depth of cut and avoid damage to surrounding tissue; however, because known devices tend to obstruct the view of the operator, if any, when in use, the necessary degree of control may be unachievable. Further, the cutting portions of these conventional devices do not include that which would prevent the destruction of living tissue, i.e., the cutting surfaces are equally suited to engage and destroy living tissue as well as other tissue or material (for example, blood deposits, thrombi, plaque, and the like). Guards, baskets, or shields can be incorporated to protect viable tissue from destructive cutters; however, visibility, compactness, and the effectiveness of the device can be compromised. Moreover, failure of a tissue protecting guard may precipitate the infliction of instant and severe trauma.
Consequently, a need exists for an intrinsically safe medical device permitting distally-positioned friable or coagulated tissue to be confronted and lysed, or dissolved, while avoiding the destruction of surrounding tissue or material. A further need exists for a device having at least one flexible member, such member generating a lysing zone which conforms to its operating environment and, when used with an endoscope, is transparent, planar, and normal to the distal tip of an endoscope to enable direct visualization of both targeted and surrounding tissue. Even with a device to satisfy these needs, a further need exists for a device capable of forcibly removing fluid as well as partially lysed tissue (including tissue particles) from the lysing site.
A device consistent with the above needs would have a plurality of applications. As an example, an uncleared fundal pool of retained blood in a stomach can preclude complete visualization of the stomach interior during endoscopic evaluation. In cases of acute upper gastrointestinal bleeding, the inability to clear a fundal pool of clotted blood in the stomach at the time of emergent upper endoscopy can result in patient morbidity and mortality. Accordingly, a need exists for a device to clear a stomach fundus of blood and other fluids and materials in patients undergoing urgent endoscopy for acute upper gastrointestinal bleeding.
As another application example, thrombotic occlusions can result in myocardial infarctions (i.e., coronary occlusions) and strokes (i.e, cerebral occlusions). While in an emergency or in an instance that such occlusions cannot readily be treated with drugs, a need remains for a device to allow such thrombotic occlusions to be rapidly and safely removed without traumatizing the surrounding tissue.
With regard to the removal of solid and semi-solid tissue following lysing, atherectomy cutters and other devices designed to remove obstructive tissues such as a thrombus, an embolism, or a massive clot in the stomach, tend to produce liquid plus a range of resultant tissue particles, including some that are large. Conventional suction of this mixture for removal and subsequent transport is frequently impossible when these particles clog a conventional, small-bore suction catheter or an endoscope working channel.
While conventional techniques include rotation of a patterned shaft within the bore of the suction catheters, this technique is susceptible to entrapping smaller tissue particles and obstructing the path of the suction catheter. In this instance, the trapped tissue merely rotates along the interior surface of the suction catheter but does not displace axially, thus preventing the transport of either tissue particles or fluid from the bodily region. Moreover, this assembly may prevent the admission and transport of larger tissue particles.